Of the games that I've played in the last few years:
EU - The
pvp is ok, but is either limited to the ring or
pvp zones that are really for elite players only. I'd give it 2 stars for
pvp.
Eve Online - This is an awesome game for
pvp as it can occur nearly everywhere and is completely free form as to the scenario. Definitely a 5-star
pvp game.
LOTRO - Meh... it was ok for
pvp, but was certainly not the focus of the game. It seemed like an afterthought project that was not given full attention of anybody. 3 starts though for fun for what's there.
Warhammer - It is a
pvp and rvr (realm vs. realm) game. However, for
pvp you run the same scenarios over and over and over again, which gets to be a grind. RvR is better in WAR as it involved attacking keeps and towns. To get to an effective level for RvR though, you have to be higher levels... there just isn't as much RvR at the lower levels. 4 stars for Warhammer
pvp.
Second Life - Lol, you can actually
pvp in SL. I wouldn't bother though... 1 star.
WoW - Well, it does have some decent
pvp in the larger scenarios, but the smaller ones get tedious and grindy. 3 stars as well.
Afterwold -
PvP almost everywhere. The whole game is pretty much
pvp, but since it's still in alpha there isn't as much
pvp as there will be upon release. 4 stars for potential.
Runes of Magic - This is a decent fantasy MMO that was recently released, and supposedly has decent
pvp. I won't rate it since I didn't actually
pvp in it.
Of course, there are a lot of games that are solely
pvp based. My favorite of these is
Global Agenda. 4.5 stars for their
pvp.
Also,
Darkfall is supposed to have some great
pvp, but I haven't checked it out yet.